Artificially induced protogyny: an advance in the controlled pollination ofEucalyptus

Abstract

Artificially induced protogyny (AlP) is a new technique for the controlled pollination of Eucalyptus, without emasculation. AlP involves cutting off the tip of the operculum of the mature flower bud just prior to an thesis, with the cut positioned so as to remove the stigma, and then applying the target pollen to the exposed cutsurface of the upper style.In trials in Brazil and Australia, rates of capsule retention and seed yield, and therefore yields of seeds per bud pollinated, have been very similar for AlP and one-stop pollination (OSP). However, AlP has achieved a 3-18-fold increase in productivity over OSP and conventional (three-visit) methods, in terms of seed produced per operator hour.Contamination levels in the Brazilian experiment ranged from 3.75% in buds pollinated at the ripe/yellow stage, to 0.77% in buds pollinated at the immature/green stage. The yield of2.0 seeds per bud pollinated with AlP at the immature/green stage was unacceptably low compared with 17.2 seeds per bud at the ripe/ yellow stage. Molecular genetic analysis of seedlings produced from one of the E. grand is x E. camaldulensis crosses in Australia confirmed that all 20 seedlings were from the target cross.The high operator productivity and relatively low levels of contamination achieved with AlP, across several eucalypt species, make it a potentially attractive technique for operational crossing. Our experiments were carried out in indoor clone banks that contained very few potential insect pollinators, so self-pollination is likely to be the main source of the contamination observed in the Brazilian experiments. Higher levels of contamination from non-target outcross pollen may occur following AlP on trees exposed to normal levels of pollinator activity.

Controlled Pollination Methods for Creating Corymbia Hybrids

“…Within AIP treatments, bud maturity at pollination (semi-ripe, green buds or ripe, yellow buds) and the use of exclusion bags had little effect on operator speed. ASSIS et al (2005) also reported increased operator speed as a major benefit of the AIP method, with, time savings of 70 % and 90 % respectively over the OSP and conventional pollination methods using smaller flowered E. urophylla, E. grandis and E. grandis x E. urophylla hybrids as maternal parents. As smaller flowers are more difficult to handle, the time benefits of AIP will increase as flower size decreases.…”

“…Exclusion bags are then used to prevent contamination with foreign pollen until the style is not receptive. However, as emasculation is not performed, there is an increased likelihood of self pollination occurring, particularly where highly self-compatible species are used (ASSIS et al, 2005). Strategies that have been assessed to minimise the levels of pollen contamination when using the AIP method include the use of semi-ripe, green buds (ASSIS et al, 2005;HORSLEY et al, 2010) and post-pollination application of sodium alginate gel to the cut style surface (HORSLEY et al, 2009).…”

“…Artificially induced protogyny (AIP) is a recently developed method of controlled pollination (ASSIS et al, 2005), which has produced greater productivity rates than the OSP method for some Eucalyptus species (HORSLEY et al, 2010). This technique does not require emasculation, involving a cut to remove the tip of the operculum and the stigma, with pollen then immediately applied to the cut surface of the upper style.…”

Adaptabilidade de híbridos multiespécies de Eucalyptus ao Estado do Rio Grande do Sul

“…O Estado do Rio Grande do Sul é um dos locais no Brasil onde a hibridação mais se desenvolveu nos últimos anos, existindo relatos da produção, plantios experimentais e comerciais de híbridos de E. urophylla x E. globulus, E. urophylla x E. grandis, E. urophylla x E. viminalis, E. urophylla x E. dunnii, E. grandis x E. dunnii e E. grandis x E. pellita, (ASSIS, 2000;ASSIS et al, 2005;MAFIA, 2007). Entretanto, considerando que a produtividade do Eucalyptus é afetada pelas variações nas condições edafoclimáticas desse Estado (COSTA et al, 2009), o sucesso de sua cadeia florestal dependerá, em grande medida, do uso de híbridos e clones com potencial para se adaptarem a essas diferentes condições.…”

Computer Simulation for the Evaluation of Recombination Strategies in Intrapopulation Recurrent Selection in Eucalyptus

“…With the ease of artificial hybridizations in eucalyptus (ASSIS et al, 1993;ASSIS et al, 2005), the use of full sibs is viable, in which recombination is directed and therefore more efficient than free interbreeding. In addition, the best individuals of the best progenies may be cloned for more intensive evaluation in clone tests, as well as allowing various copies of the same tree to be obtained for recombination.…”